Electric phonograph



June 24,1930.

A. A. THOMAS v ELECTRI C PHONOGRAPH Original Filed March 4, 1927 3 Sheets-Sheet 1 R O T N E V m June 1939- A. A. THOMAS ELECTRIC PHONOGRAPH Original Filed March 4, 1927 3 Shefbs-Sheei INVENTOR June 24, 1930.

A. A. THOMAS ELECTRIC PHONOGRAPH Original Filed March 4, 1927 5 Sheets-Sheet I 5 INVENTOR Patented June 24, 1930 PATENT OFFICE ADOLPE A. THOMAS, OF NEW YORK N. Y.

ELECTRIC PHONOGRAPH Application filed March 4, 1927, Serial No. 172,610. Renewed April 7, 1928.

My invention relates to electric phonographs in which the stylus vibrations are converted into electric impulses for operating a diaphragm. The phonograph of my invention is hornless and is characterized by a loudspeaking diaphragm mounted in a movable frame that carries an electric reproducer.v The frame is mounted to travel horizontally over the record during playing operation, and the impulses of the electric reproducer are utilized to operate the diaphragm in accordance with the stylus vibrations. For this purpose, an electric driving unit is carried by the frame in operative relation to the diaphragm.

In a preferred embodiment of my invention, the frame that carries the diaphragm is normally supported in upright playing position and is readily swung down into orizontal rest position over the turntable. On account of this novel construction, the reproducing mechanism may be housed in asmall space, and this feature renders my invention articularly applicable to electric 5 phonograp hs of the portable type. I also provide an automatic switch control for opening certain connections in the reproducer circuit when the diaghragm is in horizontal position, so as to revent waste of current when the machine is not in use.

In order that my invention may be fully understood by those who are versed in this art, I shall describe two illustrative embodiments thereof as shown in the accompanying drawings, in which- Fig. 1 shows a side elevation of an electric phonograph constructed in accordance with my invention, the loudspeaking diaphragm being shown in upright playing position;

Fig. 2 represents a plan view showing the diaphragm in horizontal rest position over the turntable;

Fig. 3 is a plan view of Fig. 1;

Fig. 4 shows a detached perspective view of the adjustable support for the frame on which the diaphragm is mounted;

Fig. 5 is a sectional view of the support illustrated in Fig. 4, the full lines showing the position of certain parts when the diaphragm is horizontal, and the dotted lines indicating the position of the parts when the diaphragm is in upright playing position;

Fig. 6 is an enlarged side view of my new electric reproducer attached to the edge of the diaphragm-supporting frame;

Fig. 7 shows an edge view of the reproducer, partly in section;

Fig. 8 illustrates a modified form of mounting for the reproducer frame, certain parts being in section for clearness, and the frame being in upright playing position;

Fig. 9 is a plan view of Fig. 8, with the diaphragm in horizontal rest osition;

Fig. 10 is a side view of ig. 9, certain parts being in section for greater clearness;

Fig. 11 represents a view similar to Fig. 8, looking in the direction of arrow a in Fig. 9 to show certain parts more clearly; and

Fig. 12 indicates diagrammatically an electrio-amplifying system between the reproducer and the loudspeaking diaphragm.

Referring to Figs.'15, an upright support 1 is fixed on the motorboard 2 of the casing or cabinet in which the phonographic. mechanism is housed. I have not considered it necessary to show any part of the cabinet, since any suitable design or construction of cabinet may be used. The dotted line 3 in Figs. 1 and 3 is supposed to indicate'the front of the machine, from which it is most convenient to manipulate the playing mechanism. On the motorboard 2 is mounted a rotary turntable t adapted to be operated by a suitable motor (not shown), which may be mechanical or electrical. There are several types of phonograph motors on the market. The support 1 is here shown as a hollow metal post secured to the motorboard by screws or bolts 5. Inside the post are bearings 6 which support a pin or stud 7 These bearings may be cast integral with the 0st. On stud 7 is pivoted an arm 8, whic terminates in a hub or bearing 9 adapted to support a swivel 10. A pair of ears or lugs 11 provided on swivel 10 Support a pin 12 on which is pivoted an extension 13 of a large frame 14 carrying a loudspeaking diaphragm 15. In the present 100 practical shape, such as oval, elli tical, o;

polygonal. The shape of the rame, course, depends upon the particular form of a diaphragm used. A 12-inch or 14-inch diaphragm gives very satisfactory results, but for a large cabinet a correspondingly larger diaphragm may be used. The directacting diaphragm 15 is secured to the rim of frame 14 in any practical way, as by a clamping ring 16 held in place by screws 17. The frame 14 is provided with integral radial arms 18, which terminate at the center in a cylindrical support .19 adapted to re ceive an electric driving unit 20. A set-screw 21, or any other suitable means, holds the unit rigidly in support 19. I need not show or describe any details of unit 20, because any practical form of electromagnetic driver for the diaphragm may be employed, such devices being well known in the market.

An electric reproducer indicated as a whole by E is attached to the frame 14 in record-playing position. This reproducer comprises a permanent steel magnet 22 secured to the rim or edge of frame 14 by screws or rivets 23, or otherwise. The magnet 22 has a pairof pole pieces, 24 and 25 arranged substantially in vertical alignment, except'that the face of the upper pole piece 24 projects slightly beyond the face of the lower pole piece 25, as best shown in Fig.' 7. To the upper pole piece 24 is'secured one end of a magnetic spring blade 26, as by rivets 27. The member 26 constitutes an elastic vibratory armature, which carries at its lower end a suitable stylus holder 28. The stylus 29 shown in the drawings is representative of any implement adapted to operate in a record groove. The position of reproducer E in Fig. 1 is for playing lateralcut records, but it is clear that this reproducer may also be mounted to play verticalcut records. The flat armature blade 26 is arranged in the plane of maximum strength, and so it easily supports the weight of frame 14 and all its parts without tending to buckleor bend laterally. At the same time, the armature is free to vibrate laterally of its own plane under the action of a recordplaying stylus. A generating coil 30 is fixed between pole pieces 24 and 25, and surrounds the armature 26 without interfering with" its vibratory movements. Referring to Fig. 7 as the armature 26 vibrates laterally, the airgap 31 is varied correspondingly and current impulses are generated to coil 30, as will be understood by those who know anything about electricity. The impulses in coil 30 are electric representations of the 'mechanical movements of stylus 29, and

they are utilized through suitable connections to operate or control the driving unit 20 of diaphragm 15.

In the playing of records, the diaphragm frame 14 is held in upright position, but is capable of swinging horizontally over the record and is also free to move vertically. The horizontal swinging movement of the frame is about the swivel 10, which is held in the fixed vertical bearing 9 of arm 8. Vertical movement of frame 14 is permitted by the horizontal pivot mounting 12 in swivel 10. The supporting arm 8 is rigidly held in horizontal position on post 1 by being lockedin a slot 32 of the post. A shoulder 33 on arm 8 rests on the bottom edge 34 of slot 32 to support the arm in horizontal position, as will be clear from Figs. 4 and 5. Now, by swinging the horizontal arm 8 on its pivot7 into vertical position, as'shown in full lines in Fig. 5, the frame 14 and the parts carried thereby are moved into horizontal rest position close over the turntable, and the lid of the cabinet may be closed.

This provides a compact construction particularly useful in portable honographs, where the carrying case shoul be as small as possible. I call attention to the fact that the frame 14 is automatically held in either position without the need of any special ockingdevice. When the frame is swung from vertical playing position to horizontal rest position, the engagement of arm 8 with post 1 along the rear edge 35 (see Fig. 5) acts as an automatic stop. Since the pin 12 is now to the rear of stopping edge 35, the center of gravity of frame 14 and its parts automatically holds the vertical arm 8 against the wall of the post. Conversely, when the frame 14 is swung back into vertical playing position, the arm 8 is automatically locked in horizontal position by slot 32, so that the now vertical bearing 9 acts like a fixed pivot for the horizontal movements of the frame and its diaphragm in the playing of records.

In finely grooved records with an electric reproducer, suoh as records, made by the modern electric recording process, the weight at the stylus point should be considerably lighter than in mechanical phonographs. To reduce the weight or pressure of frame 14 and its parts to the proper amount, I

provide a coil spring 36 secured at its upper ords, where the spiral track is almost microscopic, the stylus pressure may be less than frame 14 from vertical to horizontal position and vice versa. To prevent the spring from contracting too much and thereby pulling the frame too far to one side in horizontal position, I arrange a cross-piece39 between. the members 13 and 37. This cross-piece may be attached either to the extension 13 (as shown in Fig. 1) or to the lower arm 37. During record-playing operation, the part 39 does not interfere with the vertical movements of reproducer frame 14. However, when the frame is in horizontalrest position, the spring 36 contracts until the cross-piece 39 strikes the arm 37 and thereby locks the frame 14 against further swinging movement underthe action of the spring. I may also provide a stop 40 on extension 13 to hold the diaphragm frame against downward movement below a predeterminedpoint. The stop 40 is of such length that it engages the bearing hub 9 before the stylus of the reproducer strikes the motorboard when the vertical frame 14 is swungaside and allowed to drop. Thus, when a person is through playing a record and swings the frame to one slde of the turntable to put on a new record or to change the needle, 'he may safely let go of the frame without danger of injuring the reproducer or marring the motorboard, because the stop 40 sustains the frame before the needle in the reproducer can strike the motorboard. In other words, the stop 40 holds the reproducer frame in vertical rest position. I

The movements of the'reproducer frame 14 from vertical playing position to horizontalrest position, and vice versa, may be utilized to control automatically a reproscrew or rivet 46, or in any other practlcal way. As long as the arm 8 is horizontal, which is the position it occupies when the reproducer frame 14 is in vertical playing position, the switch contacts 42 and 43 are closed. However, when the reproducer frame is swung into horizontal rest position by moving .the arm 8 into vertical position, the .lug 45 strikes the spring contact 42 and holds it away from contact 43 (see Fig. 5), thereby automatically opening the circuit and preventing waste of current.

' In the modification of Figs. 811, the

.reproducerframe 14 has an extension 47 pivoted on a pin 48 between a pair of cars 49 on a swivel 50 which is rotatably mounted in a. hollow post 51 secured to the motorboard 2. The swivel 50 is pivotally connected by a pin 52 to a bearing sleeve 53, which is pivotal'ly and slidably mounted in the supporting post 51.- The normal operative position of the parts is shown in Fig. 8, from which is capable of horizontal movement about the time, the frame is free to move vertically about the horizontal pivot 48. The pivot members 50 and 53 act like a single rigid bearing as long as their pivotal connection 52 lies withinthe supporting post. 51. To move the reproducer frame into horizontal rest position, it is only necessary to lift the sleeve 53 until the flange 54 at the lower end of the sleeve strikes the motorboard or any other suitable stop. I When that happens, the pin 52 is clear of the supporting post 51 and the swivel 50 may now be tilted down to horizontal position, as shown in Figs. 10 and 11. A rigid arm or bracket 55 projecting from (or integral with) the support 51 terminates in a recessed head 56 adapted to receive the extension 47 of'the reproducer frame and hold the same in horizontal position. The extension 47 may fit snugly between the side flanges of head 56. To move it will be seen that the reproducer frame 14 position, it is swung upwardly about pivot 52 to bring the swivel 50 in vertical alignment with sleeve 53, whereupon the swivel slides down into the hollow post 51 until the flange or shoulder 57 of the swivel rests on top of the post, as seen in Fig. 8. The flange 54 at the bottom of sleeve 53 may bethe head of ascrew 58 inserted in the sleeve. An arm 59 on extension 47 is arranged .to engage the supporting post 51 to prevent the reproducer frame from dropping down on the motorboard, as fully explained in reference to the arm 40 of Figs. 1 and 2. The extension 47 is also provided with a rear arm 60 to which is connected one end of a coil spring 61. The other end of this spring is 'When the reproducer frame 14 is moved to horizontal position, spring 61 assumes the position roughly indicated in Fig. 10. The normal tension of spring 61 may be adjustable, like that of spring 36.

I preferably utilize the vertical movements of sleeve 53 to control a switch in the reproducer circuit. As shown in Figs. 8 and 10, a pair of switch contacts 63 and 64 are mounted on an insulated plate 65 secured to the underside of the motorboard. Each contact is connected to a binding post 66 on plate 65. The contact 64 is shown broken away for clearness, but it will be clear that it is mountedon plate 65in the same Way as contact 63. The latter is in the form of a spring blade having a normal set which keeps it away from contact 64. In other words, the contacts are normally open to prevent the passage of current. This openposition of the switch occurs when the sleeve 53 is raised to move thereproducer frame 14 into horizontal rest position, as shown in Fig. 10. When the reproducer frame is in vertical position, as shown in Fig. 8, the lowered sleeve 53 closes the switch contacts and holds them in closed position. If the head 54 at the bottom of sleeve 53 is of metal, an insulating strip or pad 67 is provided either on contact 63 or head 54.

Fig. 12 represents diagrammatically a simplified form of transmission system between the coil 30 of reproducer E and the driving unit 20' of diaphragm- 15. A vacuum tube 68 has its grid 69 connected to one end of reproducer coil 30, and the other end of this coil is connected to one side of filament 70, which is fed by a battery circuit 71. This circuit is of the usual type,

except that it includes a normally open 'switch 72, which may represent swltch 42'43 of Figs. 1-5 or switch 63-64 of Figs. 8-10. The plate 73 of tube 68 is connected in the usual way with a plate battery 74. A variable high resistance 75 may be shunted around the battery .to control the volume of reproduction. The plate circuit'includes a rimary coil 76 of an amplifying transormer T, and the secondary coil 77 of the transformer is connected to the driving unit v20. When the reproducer frame is in operative osition, the switch 72 is closed and the electric impulses of reproducer coil 30 are transmitted to the operating coil of the drivin unit after being amplifiedby tube 68. an transformer T. This willbe understood by those familiar with radio circuits without further explanation. When the filament switch 72 isopen, no current can flowfrom either the filament battery or the I plate battery. The normal ohmic resistance of the controlling shunt 75 is so high that practically no current flows therethrough when the machine is-not playing.

In the basic aspect of my invention, the reproducer-frame 14 me be so mounted as to he permanently in orizontal position,

gineers contend, however, that a direct-acting diaphragm gives best results when freely exposed to 0 en air on both sides. This condition is lfilled when the diaphragm is held upright in playing a record. When the reproducer frame is horizontal in' playing position, the lower side of the diaphragm is necessarily close to the record and therefore not so freely open to the outer air. But that may not be objectionable. to some persons. Both arrangements are in accordance with the basic idea of my invention. Also, instead of attaching the electric reproducer rigidly to frame .14 and having the whole frame more vertically in the playingof a record, the reproducer can be connected to the frame so as to have a limited vertical movement while travelling horizontally over a record.

Although I have-shown and described certain specific constructions, I want it undermagnetic reproducer both carried by said frame, said reproducer includinga stylusholding member mounted to vibrate laterally in relation to a magnet for generating current impulses, and electric means for operating. said diaphragm in accordance with cur-f rent impulses generated by said reproducer.

2. An electric phonograph having a frame operatively mounted over the motorboard, a loudspeakmg diaphragm carried by said frame, an electric driving unit mounted on said frame for operating said diaphragm, an electric reproducer secured to said frame for supporting a stylus in playing position, said reproducer including a laterally vibratory member for playing lateral-cut records,

means for so mounting said member that it is incapable of vertical vibration and it thus able 'to support the weight of the swinging frame, and electric connections for transmitting the current'impulses of said reproducer to said drivin unit. 7 1 e i 3. In an e ectric phonograph, a frame pivoted to have horizontal and vertical movements, a loudspeaking diaphragm .car-

ried by said frame, an electric driving unit mounted on said frame for operating said dlaphra an electric reproducer mounted on said ame at the edge'thereof to support a stylus 'in playing position, and electric connections. between said reproducer and said driving unit.

4. In an electric phonograph, a circular frame pivoted to have horlzontal and vertical movements, a cone diaphragm carried by said frame, an electric driving unit mounted centrally on said frame for operating said diaphragm, an electric reproducer secured to said frame at the rim thereof for supporting a stylus in playing position, and electric connections between said reproducer and said driving unit.

an electric reproducer secured to said frame for supporting a stylus in playing 1 position, electric means for operating said in accordance with current impulses generaated by said reproducer, and means for supporting said frame in u right playing position so that the axis 0 said diaphragm is substantially horizontal, said supporting means being adjustable tothold said frame ri 'dly in horizontal rest position.

"In an electric phonograph, a frame pivoted to have horizontal and vertical movements, a loudspeaking diaphragm carried by said frame, an electric driving unit mounted on said frame for operating said diaphragm,

an electric reproducer mounted on the edge of said frame to support a stylus in playing position, electric connections between said reproducer and said drivingl unit, and means for counteracting the weig t of said frame and the parts carried thereby to reduce the playing pressure of the stylus point to the desired amount.

8. In an electric'phonograph, a vertical frame pivoted to have honzontal and vertical movements, a lou'dspeaking diaphragm carried by said frame, an electric unit mounted on said frame for operating said diaphragm, an electric reproducer mounted on said rame at the lower ed e to support a stylus in playing position, e ectric connections between said reproducer and said driving unit, an arm' rojecting from said frame, and an adjustab e spring connected to said arm for regulating the playing pressure of I the stylus point.

, 9., 11 an electric phonograph, a circular frame carryin a cone diaphragm, an extension on sa1 frame, pivot means engaging said extension to support said frame for aphragm position.

horizontal and vertical movements, an electric driving unit mounted on said frame for operating said diaphragm, an electric reproducer secured to said frame for supporta ing a stylus in playing position, electric connections between said reproducer and said driving unit, and a substantially vertical coil spring counteracting the wei ht of said frame and the parts carried therdlay to reduce the playing pressure of the stylus point to the desired amount,

10. An electric phonograph provided with a movable frame carrying a loudspeaking diaphragm and an electric driving unit for said diaphragm, an electric reproducer attached to said extension for mounted on said frame and electrically connected with said unit, a support for holding ing position, and means whereby said frame said frame and diaphragm in vertical playand the parts carried thereby are adjustable on said support into horizontal rest position, said means including a vertically swingable arm on which said frame is pivotally' mounted, said arm beingnormally held rigid in substantially horizontal position.

11. -In an electric phono raph, a fixed up right support, a member a justably mounted v on said support and provided with a pivot bearing, means for normally holding said member rigid, a rotary vertical member mounted in said pivot bearing, a frame pivoted to said rotary member for horizontal swinging movement while said first member remains stationary, said members cooperating to hold said frame normall in vertical position, a loudspeaking diaphragm and electric driving unit therefor carried by said frame, separate pivot means for permitting vertical movement of said frame during the playing of a record, an electric'reproducer mounted on said frame and electrically connected with said drivin unit, said firstnamed member being ad ustable to permit said frame to be swung on said support into horizontal rest position and coo crating means on said frame and support fiir holding the frame in horizontal position.

12. In an electric phonograph, a fixed up- I right support, an arm pivoted on said support and normally held thereon rigidly in horizontal position, a bearing provide on said arm, a swivel mounted in said bearing, a frame plvoted to said swivel and normally held in upright position for vertical and horizontal movements, a loud-speaking diaphra and electric driving unit carried by said; rame, and an electric reproducer 4 mounted on said frame and electricall connectedgwith said driving unit, said pivoted arm being movable into vertical position on said support to swing said frame and all parts carried thereby into horizontal rest anelectric phonograph, a movable frame carrying a loudspeaking diaphragm, an. electric driving unit mounted on said frame for operating said diaphragm, an electric reproducer secured to said frame for supporting a stylus in playing position, electric connections between said reproducer and said driving unit, means for supporting said frame in upright playing position, said supporting means being ad ustable to hold said frame in horizontal rest position, and means whereby said electric connections are auto matically broken when said frame is moved into horizontal position.

'14. In an electric phonograph, a movable frame carrying a loudspeaking diaphragm, an electric driving unit mounted on said frame for operating said diaphragm, an

electric reproducer secured to said frame for supporting a stylus in playing position, electric connections between said reproducer and said driving unit, said connections including a normally closed switch, means for supporting sald frame in upright playing position, said supporting means being adjustable to hold said frame in horizontal rest position, and means movable with said supporting means for automatically opening said switch when said frame is in horizontal position.

. 15. An electric phonograph having a frame supported normally in upright playing position and capable of moving horizontally and vertically over the turntable, a loudspeakin diaphragm and an electric reproducer both carried by said frame, elec tric means for operating said diaphragm in accordance with current impulses generated by said reproducer, said electric means including a circuit, means for supporting said frame and dia hragm in horizontal rest position over t e turntable, and a switch adapted to be automatically opened to break said circuit when the frame is in horizontal position.

16. An electric phonograph reproducer comprising a magnet supported in such posi- 'tion that the pole pieces he one above the other in substantially vertical alignment, an

elastic armature blade fixed flatwise to the upper pole piece and extending toward the lower pole piece in a substantially vertical I plane, said armature blade being spaced from the lower pole piece, a stylus holder attached to the free end of said armature blade, and

a generating coil mounted between said pole pieces and surrounding said armature.

17. In an electric phonograph, a frame operatively, mounted to travel over a record, a loudspeaking diaphragm carried by said frame, a magnet mounted on the edge of said frame, so that the pole pieces of the magnet lie one above the other in substantially vertical alignment, an elastic armature blade fixed flatwise to the upper pole piece and extending toward the lower pole piece armature blade extends, whereby the stylus movements cause lateral vibration of said armature blade to generate current impulses in said coil.

18. In an electric phonograph, 'a'horizontally movable frame carrying a loudspeaking diaphragm, an electric reproducer operatively mounted on said frame, said reproducer having a vibratory arm held against longitudinal vibration to support the weight of said frame but adapted to vibrate laterally on lateral-cut records, and electric means controlled by said reproducer for operating said diaphragm.

19. In an electric phonograph, a frame carrying a loudspeaking diaphragm, an electromagnetic reproducer mounted in playing position at the edge of said frame, electric means controlled by said reproducer for opcrating said diaphragm, and means for operatively supporting said frame.

20. A hornless electric phonograph having a frame movable horizontally over a record, a loudspeaking diaphragm and an electric reproducerbothcarried by said frame, said reproducer including a stylus holder adapted to vibrate laterally for lateral-cut records but held against vertical vibration to support the weight of said frame when playing a record, means whereby said reproducer is also capable' of vertical movement, and electric means for operating said diaphragm in accordance with current impulses generated by said reproducer.

21. An'electric loudspeaking reproducer for phonographs movable as a unit over a playing record on'the turntable, said unit comprising a frame, a loudspeaking diaphragm carried by said frame, electromagnetic mechanism for operating said diaphragm, and an electromagnetic reproducer mounted at the edge of said frame for controllin said mechanism. v

22. s a new article of manufacture for use in electric phonographs, a frame carrying an electrically operated loudspeaking diaphragm, and stylus-actuated electromagnetic means mounted at the edge of said frame for producing electric impulses to operate said diaphragm, said frame being adapted to be operatively mounted for laying records;

23. An electric phonograph reproducer comprising a magnet, an elastic magnetic arm secured at one end to one pole of the magnet so as to vibrate at its free end which is spaced by an airgap from the other magnet pole, a stylus mounted on said arm as an axial extension thereof to vibrate the arm laterally and vary said airgap, and a coil influenced by the vibrations of said arm which passes through said coil.

24:. In an electric phono raph, a movable frame carrying a loudspealliing diaphragm, an electric drlving unit mounted on said frame for operating said diaphragm, stylusactuated means carried by said frame for producing electric im ulses to operate the diaphragm, means or supporting said frame in upright playing position, means whereby said frame is movable into horizontal rest position, and means whereby the reproducing circuit is automatically broken when the frame is moved into horizontal position.

25. A hornless electric phonograph having a frame supported in upright playing position, a loudspeaking diaphragm mounted in said frame, an electromagnetic reproducer secured in playin position to the lower edge of said vertical rame, and a driving unit carried by said frame for operating said diaphragm in accordance with current impulses generated by said reproducer.

- 26. In an electric phonograph, a horizontally swinging member carrying an electromagnetic reproducer which comprises a magnet, a coil in operative relation to said magnet, a flat magnetic reed. secured to one pole piece and spaced from other ole piece, said reed passing through said 0011 and being arranged in a right angles to a dis record, and a needle holder secured to the free end of said reed.

ADOLPH A. THOMAS.

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